Conventionally, lithium ion batteries have been given focus as batteries of high energy density. It has been know that lithium ion batteries obtain a high voltage potential of 3 V or higher due to using a non-aqueous solution system electrolytic solution. However, there has been a problem in that conventional lithium ion batteries have a low charge-discharge capacity density per mass of cathode material (charge-discharge capacity density).
Therefore, the present applicant proposed a battery containing rubeanic acid (dithiooxamide) or a rubeanic acid derivative (hereinafter referred to as “rubeanic acid (derivative)”) as an active material (refer to Patent Document 1). With this battery, as shown in the following formula (a), the rubeanic acid (derivative) binds with a lithium ion when reduced (discharging (a case of using rubeanic acid as cathode active material, same as below)), and releases the lithium ion when oxidized (charging (case of using rubeanic acid as cathode active material, same as below)). The lithium ion is supplied from the anode side, which contains a carbon material or silicon-tin-based material into which lithium ion is incorporated, in addition to lithium metal. According to this battery, it is said that a high charge-discharge capacity density is obtained even at room temperature or lower.
    [Patent Document 1] Japanese Unexamined Patent Application, Publication No. 2008-147015